Field of the Invention
This invention relates to an apparatus and method for reproducing a recording medium, which is used for reproducing information from a magnetic tape, etc. on which data of a computer is recorded, for instance in a rotary head type magnetic recording and reproduction apparatus.
Description of the Background Art
FIG. 1 is a view showing track patterns of a magnetic tape 41 on which data is recorded by a rotary head type magnetic recording and reproduction apparatus. Tracks A0, A1, A2, . . . are the portions recorded by a magnetic head 42a. Data on these tracks A0, A1, A2, . . . are read out by the magnetic head 42a. Also, tracks B0, B1, B2, . . . are the portions recorded by another magnetic head 42b, and data on these tracks B0, B1, B2, . . . are read out by the magnetic head 42b. The track A0 is divided into main data recording portion M and control data recording portions S1 and S2. For example, data of a computer is recorded on the main data recording portion M, and the number of data recorded in the main recording portion M is recorded in the control data recording portions S1 and S2.
The control data recording portion S1 is divided into a plurality of recording areas, and similar data corresponding to the number of data recorded in the main data recording portion M is recorded in respective recording areas. The control data recording portion S2 includes data similar to that of the control data recording portion S1. Therefore, even though a magnetic tape 41 is caused to travel in either the normal direction (the direction of an arrow 46F) or the reverse direction (the direction of an arrow 46B) at a faster speed by several times to several decades of times than usual traveling speed, it is possible to read out data from the control data recording portions S1 and S2. Tracks A1, A2, . . . and tracks B1, B2, . . . are also in a manner similar to that of track A0. A track Ai (i=0, 1, 2, . . . ) and a track Bi constitute a frame Fi.
In the case output from the computer is recorded on a magnetic tape 41 by a helical scan system such as the above DAT system or a VTR system, there may be a case that a part of data stored in the magnetic tape 41 is desired to be read out and visually displayed. At this time, data in each of the tracks recorded in this magnetic tape 41 can be reproduced and displayed in proper order, and if data of each of the tracks can be reproduced in reverse order, it is very convenient for searching or reference.
When the magnetic tape 41 on which data has been recorded with such track patterns as shown in the above FIG. 1 is reproduced by traveling in the opposite direction of the usual traveling direction in the rotary head type recording and reproducing apparatus, strictly speaking, when reproducing data per frame, which has been recorded on the magnetic tape 41, in the reverse sequence of the sequence of the frames (hereinafter these movements are called merely "reverse reproduction"), the magnetic heads 42a and 42b can not accurately trace the tracks by traveling along the magnetic tape 41 in the reverse direction, and it is impossible to secure accurate reproduction movements.
Namely, in FIG. 1, in recording, tracks are formed in the direction of vector 45 which expresses the sum of vector 43 which expresses the tracing direction and the tracing speed of the magnetic heads 42a and 42b and vector 44 which expresses the tracing direction and the traveling speed of the magnetic tape 41. Therefore, in the case the magnetic tape 41 is caused to travel in the direction of vector 47, the magnetic heads 42a and 42b trace on the magnetic tape 41 in the direction of vector 48 which is the sum of the vector 43 and the vector 47, thereby causing the magnetic heads 42a and 42b to inaccurately trace on the tracks.
Hence, in the case of reverse reproduction, firstly the magnetic tape 41 is caused to travel in the reverse direction and comes to a stop after the magnetic tape 41 travels for a specified distance. Next, usual reproduction is conducted from the frame at the point where the magnetic tape 41 has stopped, to the frame from which reverse reproduction is started. Data of each of the frames reproduced therein is memorized in a memory. When data is outputted from the memory, data is outputted in the reverse sequence of the sequence of the frames on reproduction.
As the magnetic tape 41 is caused to travel in the reverse direction for a specified distance and usual reproduction is conducted when conducting the reverse reproduction in the aforementioned method, the number of frames which are reproduced per reverse reproduction is constant at all times. However, the number of data which is recorded in each of the frames is not necessarily constant. Therefore, the number of all the data memorized in the memory in a cycle of reverse reproduction is not necessarily constant. So, when the data memorized is minimal, there is a problem that the memory can not be effectively utilized.